Telephone-exchange system



1. C. McAULlFFE.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FlLlD MAR-1,1918.

' Patented Feb. 10, 1920.

' improved signaling means for jvention;theincoming end of atrunkcircuit 'o'usly to 'furn-islraguard signal, whichrev NITED STATES PATENTOFFICE.

'JoHno. MCAULIFFE, orinnw YORK, 1v. ASSIGNOR 'ro wnsrnnn'nnnormc'ooMrANY, INCORPORATED, or NEwYonmn. Y., A CORPORATION on NEW YoiiK.

- TELEPHONE-EXCHANGE. SYSTEM.

T 0 all-whom it may concern:

Be it known that I, .Jonn O. MoAuL1rrn, a citizen'of the United States,residing at New York, in the county 01? 'New .York, State of NewYork,.have invented certain new and useful'lmprovements in Telephone-Exchange Systems, of which the following His-a full, clear, concise, andexactdescrip- .t i'on.

This invention relates to telephone exchange systems and moreparticularly to "such systems-employing trunk circuits forinterconnecting telephone lines terminating at different switchboards.

The obj ect of this invention is to provide ln'accordancewith a featureof thisinis provided with ;a signaling device .which, when a linkcircuit is-connected with the "outgoing-end thereof,=is operatedcontinumains so operated after "the trunk circuit hasbeenc'oiniectedwith a telephone lineuntil'the receiverthere'ofisremovedifrom the switchhook to furnish a ringing'signahand which isintermittently operated to furnish a. disconnect signal when the linkcircuit is disconnected from the outgoing end of the trunk circuit.

For a linore complete understanding of.

this invention-reference should be had to the followingdescriptionconsidered in I 0911- V nection with "the accompanying, drawingillustratin'gone embodimentthereof. I

As shown in the drawing-a telephone line A terminates at oneeswitchboardwhere it, is

-'connected with a link-circuit B. A trunk circuit C- 'eXtends from thefirst to a second switchboard *and serves, whenithe llIlk circuit-B isconnected therewith, to eXtendt-he position, whilelthat shown to theright of Kthisllineis associated with thesecond switch- .or'..B,operators position.

." The;:subscriber.,Aehavingl aced ,a -a11- .ins the usual. manner vand.the cord circuit; B

such systems.

Specification of Letters Patent. Patented-Feb;10,1920. Application filedMarch 1,-1 91 s; Seria1 No.'219,786.

having beenconnected therewith, the P A operator may actuate listeningkey 6 to connect the operators telephone set with the telephone line.Upon being advised that subscriber A desires to be connected with theline which terminates at the second switchboard, the A operator restoresthe listening key 6 to normal position and communicates over an orderwire circuit (not shown) with the FB operator of the. second switchboardand receives a trunk assign ment.

Assuming the trunk assignment ;to be trunk circuit 5G, the .Aoperatorinserts calling plug? of the cord circuit -B into jack 8'0fthe'trunk circuit 'C, whereupon calling supervisory lamp 9 is lightedover a circuit from battery through the lamp :9, resistance '10, sleevecontacts of the plug 7 and the jack'S and resistance v11. to ground.Trunk relay 12 is also operated over a circuit from battery through thewinding of calling supervisory .relay 13, ring contacts voflthe plug 7and jack ,8, the windings" of the trunkrelay 12, and tip contactsof thejack 8 and the plug 7 to ground. LOalling V supervisory-relay 13 doesnot now operate vbecause of the high resistance of the lefthand windingof thetrunk relay 12. The

trunk; relay 12 in operating causes the lighting of lamp 15 and theoperation of relay. 16. The lamp islighted over a circuitfromrbatterythrough the lamp .15, normal contact and lower winding of relay.1'7, andcontact of thetrunk relay 12 toground. The lower winding of relay 17 issuch that :therelay does not receive sufficient currentato cause it toopen its-normal and closeits alternate contacts. Relay 16, in operating,.opensfits left-hand and closes its right-hand contact;

The lighting of thelamp'15 serves has an indication to the trunk or i B,operatorthat the A. operatorhas connectedrwithzthe assigned trunkcircuit. The B operator may thereupon insert plug 18. offthestrunkcircuit Ginto jack 19.01? the ,telephonelline D, itbeing assumed.thatconnectionis desired with lZGlGPlIOIlGllllGiD. Upon the insertionof the plug.18. into the j ack..19,..relayl17 of the trunkzcircuit and'cutofi' relay '20 of thetelephoneline are operated over a circuit fromi battery .through t'theklamp .15,

upper winding ofrrelayl Iipsleeve contacts ofthe plug 18 and the ack 19and the winding of the cutoff relay 20to ground. Relay 17 in operatingopens its normal contact and closes its alternate contacts. The lamp 15remains lighted. V V

Subscriber D may be signaled in any desired manner. Upon the removal ofthe re- Ceiver from the switch hook, supervisory relay 25 is operatedover a circuit from bat-- tery through the winding ofrelay 25, ringcontacts of the plug 18 and the jack 19, out over one side of the line,through the switchhook contact, back over the other side of the line,tip contacts of jack 19 and the plug 18, and the upper alternate contactof relay 17 to ground. Relay 25, in operating, connects the lowresistance left-hand winding of relay '26 in parallel with thehighresistance lefthand winding of trunk relay 12. A The resistance incircuit with the calling supervisory relay 13 is thereby reduced,permitting the operation of this relay. Relay-'13 in operatingestablishes a shunt circuit, including resistance 27, about the lamp 9which is thereby eflaced. Relay 26operates, establishing a shunt circuitfor the lamp 15, which may be traced from battery through theright-handcontact of relay 16, the righthand winding and the contact ofrelay 26,

lower alternate contact of relay 17. This shunt circuit is of lowresistance, so that the lamp 15 is effaced.

At the conclusion of the conversation, subscriber- D, in restoring. thereceiver to the switchhook, causes the release of relay 25, removingtheleft-hand winding of relay 7 r 26 from parallel relation to theleft-hand winding of trunk relay 12, thereby increasing the resistancein circuit with the calling supervisory relay 13. This supervisory relay13 thereupon releases its armature, causing the calling supervisory lamp9 to be lighted to furnish a disconnect signal. Subscriber A inrestoring the receiver to the switchhook causes the lighting of theusual answering supervisory lamp (not shown). The lighted supervisorylamps of the cord circuit B serve as disconnect signals, whereupon the Aoperator may withdraw the plug 7 from the jack 8. Trunk relay 12 Ithereupon releases, and in releasing opens the energizing circuit ofrelay 16. Relay 1 16 thereupon opens its right-hand contact,

which is in circuit with the relay 26. Re-

lay 26 thereupon releases its armature, opening the shunt clrcuit aboutthe lamp 15. The

closure of the left-hand contact of relay 16- upon the release thereof,establishes aninter- I mittent shunt circuit for the lamp 15, which dmay be traced from battery through inter- V rupter 28 and resistance 29,left'hand contact of relay 16 and the lower alternate contact of relay.17. The lamp 15 is thereupon intermittently lighted'to furnish a disconf nect signal to the "B operator, who may thereupon withdraw the plug 18from the jack 19, restoring all apparatus to normal. condition.

From this brief description it will be clear that the lamp 15 iscontinuously lighted 1. A telephone exchange system:compris-- ing atrunk circuit extending from a first to a second switchboard, atelephone line terminating at a second switchboard and connected withthe trunk circuit, allnk circuit at the first switchboard, a signalingdevice at the second "switchboard operating upon the connection of thelink circuit therewith, a relay in the trunk circuit responsive to theclosure of the telephone line upon the removal of the receiver from theswitchhook for-stopping the operation of the signaling device, anda'relay responsive to the disconnection of the link circuit from thetrunk circuit to cause the intermittent operation of the signalingdevice.

2.. A telephone exchange system comprising a trunk circuit extendingfrom a first to a second switchboard, a telephone line terminating atasecond switchboard and connected with'the trunk circuit, a link circuitat the first switchboard, a signaling device at, the second switchboardoperating .upon the connection of the link circuit therewith, a relay inthe trunk circuit responsive to the closure of the telephone line uponthe removal of. the receiver from the switchhook for stoppingthe'operation of the signaling device, and interrupter mechanismincluded in circuit. with the signaling device uponthe' disconnection ofthe link cir- 3. A telephone exchange system comprisinga trunk circuitextending from, a, first cuit from the trunk circuit to cause theintermittent operation ofthe signaling device.

to a second switchboard, a link circuit at the firstswitchboard, atelephone line terminating at the second switchboard, asignaling devicein the trunk circuit, a relay in the trunk circuit energized in responseto the connection of the link circuit therewith for causing theoperation of the signalingcuit with. the telephone line, a relay "inthetrunkcircuit energized over the connected telephone line 'forcontrolling theYsignaL ing device, and an interruptermechanism'broughtinto'operative relation with thesig- 'nalm'g deviceby thedeenergization of the evice, means for connecting the trunk cirfirstrelay following the disconnection of the link circuit from the trunkcircuit for causing the intermittent operation of the signaling device.1

4:. A telephone exchange system comprising a trunk circuit extendingfrom a first to a second switchboard, a telephone line terminating atthe second switchboard, a link circuit at the first switchboard, asignaling device in the trunk circuit, a relay in the trunk circuitenergized in response to the connection of the link circuit therewith, asecond relay in the trunk circuit cooperating with the energized relayfor causing the operation of thesignaling device, a circuit establishedby the connection of the trunk circuit with the telephone line forcausing the energization of the second relay and for maintaining thesignaling device operated, and an interrupter mechanism brought intooperative relation with the signaling device by the denergization of thefirst relay following the disconnection of the link circuit from thetrunk circuit for causing the intermittent operation of the signalingdevice.

In witness whereof, I hereunto subscribe my name this 16th day ofFebruary, A. D.

JOHN C. MOAULIFFE.

